Technical Field
The disclosure belongs to the technical field of semiconductor power devices, particularly relates to a semi-floating-gate power device and a manufacturing method thereof.
Prior Art
Compared with a traditional silicon device, a wide band-gap device with high electron mobility, such as a gallium nitride high-electron-mobility transistor, has the advantages of high temperature resistance, high efficiency, high speed and the like, and has been widely used. Currently, a 600V gallium nitride high-electron-mobility device is difficult to be manufactured into a normally off type. Even if the device is manufactured into a normally off device, the threshold voltage of the device is close to 0V, and the device is easily opened by mistake. Therefore, the 600V gallium nitride power switch is usually composed of a normally on gallium nitride high-electron-mobility transistor device and a normally off silicon-based device which are connected by a common source and a common gate.
In the prior art, the circuit of the gallium nitride power switch with common source and common gate is as shown in FIG. 1, and the switch comprises a normally on gallium nitride transistor (MGaN) and a normally off silicon-based MOS (metal-oxide-semiconductor) transistor (MSi) which are connected by the common source and the common gate. Wherein, the silicon-based MOS transistor (MSi) is actively controlled by a gate driver, and the gate driver generates a gate signal (VGM). The gallium nitride transistor (MGaN) is indirectly controlled by the silicon-based MOS transistor (MSi), because the drain-source voltage of the silicon-based MOS transistor (MSi) is equal to that of the gallium nitride transistor (MGaN). The common-source and common-gate gallium nitride power switch has the advantage that the gate driver which meets existing standards can be used, so the common-source and common-gate gallium nitride power switch can directly replace a silicon-based MOS transistor switch. However, the common-source and common-gate gallium nitride power switch comprises the normally on gallium nitride transistor (MGaN) and the normally off silicon-based MOS transistor (MSi), has a complicated structure and has low reliability. Firstly, in case of the dynamic avalanche of the common-source and common-gate gallium nitride power switch, the low-voltage normally off silicon-based MOS transistor is easily broken down; secondly, because the gallium nitride transistor has voltage pulse in dynamic operation, the transistor also has the problems of breakdown, reverse connection of pn junction of gate, etc.